The slugfest — which was moderated by a CNBC host at the channel’s New York Stock Exchange studio — so captivated traders on the exchange floor than when either billionaire landed a solid verbal blow a very audible “Whoa!” could be heard from the traders below.

It was not unlike the reaction from the crowd at a heavyweight fight when one boxer gets knocked to the floor.

Icahn called Ackman a “crybaby in a school yard” while Ackman shot back: “Carl Icahn does not have a good reputation for being a handshake guy.”

Icahn counter-punched, calling Ackman a liar and a “major loser,” saying “I rue the day I ever met the guy.”

“He’s a bully,” Ackman shot back.

The debate continued at a heated pace nearly from start to finish — with CNBC not breaking for any commercial spots.

As the two traded barbs — most of which centered on an 8-year old legal battle that Ackman finally won in 2011 — Herbalife shares danced like an EKG readout, but eventually settled pretty much unchanged after the half hour.

Ackman announced to much fanfare on Dec. 19 that he made a $1 billion short bet against the nutritional supplements company because he thinks it’s a pyramid scheme that will be shut down by regulators.

Icahn charged Ackman with grandstanding by announcing the short before an audience. He suggested Ackman should join the Securities and Exchange Commission if he wanted to accuse Herbalife of fraud.

Ackman claimed Icahn used the same conference a decade ago to announce shorts of his won.

Both said repeatedly they have no use for the other guy.

Icahn kept referring to his hedge-fund world rival as “this Ackman guy.”

The two couldn’t even agree on where a meeting 10 years ago occurred — Icahn said it was in his office while Ackman maintained it was over the phone.

At first, Ackman’s appearance on CNBC was to be a solo act — merely to counter Icahn’s charges from the previous day.

But then Icahn called into the show — perhaps invited by a CNBC producer — and Ackman agreed to discuss Herbalife.

The rest was TV gold.

Icahn was even in a feisty mood with the CNBC moderator, Scott Wapner, claiming the host was trying to bully him by asking whether he would confirm that he is long Herbalife, which The Post reported exclusively on Jan. 10.

“I didn’t get on here to be bullied by you,” Icahn shot back. “I’m not going to talk about my Herbalife position. I’m never going on CNBC with you again.”

Later, when he defended Herbalife against Ackman’s short, Icahn admitted “I wouldn’t care if it was anybody else but Ackman.”